Speaker : Antarjami Sahoo

2018-11-22

Abstract :

Modern electronic devices are based on thin film multi-layers, which consist of hetero-interfaces. Thus, the study of interfacial properties of different combinations of materials is very essential for enhanced functionalities and/or novel device concept. The interfacial properties of a series of superlattices consisting transition metal oxides have been studied. The orthorhombic exhibits metal-like electronic transport, ferromagnetic ordering with negative spin polarization, strong uniaxial crystalline anisotropy, relatively large coercive field and a Curie temperature of in its bulk form. While orthorhombic shows insulator like electronic transport with antiferromagnetic ordering of below the Néel temperature 100 K. The thin film of grown on substrate gets stabilized in tetragonal structure with resultant ferromagnetic ordering with Curie temperature . The breaking of orthorhombic to tetragonal crystal symmetry is realized by increasing the layer thickness in the superlattices consisting of 17 unit cell thick . By stabilizing tetragonal symmetry, we have achieved a very strong in-plane antiferromagnetic(AFM) ordering, perpendicular magnetic anisotropy, two-step magnetic switching, the robust dual exchange bias in the temperature and/or field dependent magnetization, and tunneling like transport with anomalous anisotropic behavior observed in field dependent magnetoresistance. These features are analyzed using Meiklejohn-Bean model, Stoner-Wohlfarth model and density functional theory [1,2]. On the other hand, the orthorhombic crystal symmetry is associated with the weaker interfacial AFM ordering and stronger spin-orbit coupling due to the reduction in Ru 4d orbital occupancy and larger orbital overlapping, respectively. These host of observed interesting physical properties, which are the intriguing phenomena in modern spintronics based devices and their tunability could pave the way for new technology.